2. speakers
  3. 1348847881

Soundlab Speakers - Budget Amp Suggestions

I have tried to read as much as possible about different types of amplifiers capable of driving electrostatic speakers. Thanks to everyone for the great articles and discussions. In particular, I am looking for a ss amplifier that can drive Soundlab speakers. The Soundlabs have a low impedance at high frequencies and a high impedance at low frequencies. A high power ss amp that can drive difficult loads appears to be the ticket (I'm not interested in tube amps). High current is needed for the high frequency/low impedance (but not necessarily high power) while the high voltage (albeit at lower power) can drive the high impedance at low frequencies.

While looking for speakers I came across the Soundlab speakers and really liked the sound. I basically blew my budget on them, which for me is not a bad compromise because I don't want the speakers to be the weak link in the chain.

So this is what I have:
1. Two Soundlab A-1 speakers (1992 vintage)
2. One Soundlab B-1S subwoofer (pre 1990) - This is a stereo subwoofer having two separate inputs to drive each interior panel.
3. The A-1s have the toroidal and impedance upgrade.
4. I had all the speakers reskinned with the px mylar.

There will be some type of crossover between the A-1s and the B-1S (the frequency and type of crossover is undetermined at the moment)

I believe that having the B-1S reduces some of the constraint of having the highest power amplifier to drive the A-1s (e.g. 500-600W) since a lot of the bass will be coming from the B-1S. I was told to limit the power to the B-1S to a 400W or less ss amplifier. I am thinking that perhaps I could get away with a lower power amplifier for the A-1s because of this scheme. Please let me know if I am wrong.

As I said my budget is limited. I have about 1.2K and perhaps up to 2K to spend on an amp. The amp I have targeted is a Sunfire Cinema Grand Series II 5-Channel amplifier that outputs 425W a channel. The channels driving the B-1S won't be delivering a lot of power as the impedance is 16 to over 30 ohms. The amp should be able to drive the A-1s adequately. As a side note I have a couple of amps (Crown K1 or Citation 7.1 which output between 300-400W) that I could use to drive the B-1S if needed.

Are there some vintage or other budget amps that I should be considering. Is my analysis wrong? Any suggestions on crossover frequency? I appreciate any and all input. I want to thank every one in advance for their thoughts.

Regards,
GWHO

gwho
gwho OP
47 posts
 
Stringreen,

I do have a budget and I chose to spend most of it on the speakers. The speakers that I purchased are twenty years old although they do sound good. They are not current top of the line. I believe that my choice of amplifier is critical because of the difficult load the Soundlab imposes. The suggestions provided by the contributors to the thread are all good. The Innersound, Sunfire, TNT-200, and Odyssey Monos amplifiers have all been proven to have good SQ with the Soundlabs. Moreover, they are all within reach of my budget which does not make any of them a compromise. Just good amps for my speakers.
grannyring's avatar
grannyring
6,464 posts
 
The CJ MF2500a is also very special. Not as powerful as the Sunfire, but sounded better and had enough power as an FYI. These "budget" amps can hold their own with big dollar amps. They will make the SL's sing!
tthomas
36 posts
 
Bass response was one of the things that surprised me the most when I went to the Odyssey monos. It seemed to me that they handled the panel better than my old amps. I initially bought my SLabs from a long time SL dealer and he actually was the one that talked me into the Odysseys since I could not afford the big AtmaSphere amps. I have borrowed a few amps since then, but for my budget these have been the best.
gwho OP
47 posts
 
So now I've come full circle. I have a great list of amplifiers I should look into that have been proven to work with Soundlabs. I will restate one of my initial questions. I am less constrained on my A-1s in requiring high voltage on the low end since I have the planar bass panel that I can drive with a separate amplifier. Would I be better off going with a lower power but higher resolution (on the high end) amp for the A-1s such as the mf2500a or the Odyssey Monos. Are we talking about very subtle or significant differences in sound signature.

One thing that I have decided is that I am going to try more than one of these amps to settle on one that I like.
atmasphere's avatar
atmasphere
11,764 posts
 
Gwho, I realize that the budget is an issue but one thing you will have to face it its really hard to get Sound Labs to sing if you have transistors. Transistors as you know try to double power as the impedance of the load is halved, which is another way of saying that they cut power in half if the impedance is doubled.

With the Sound Labs both ways of looking at this are a concern. On the bottom end you can't make power, on the top end there is a tendency to make too much. To give you an idea, a 150 watt tube amp can easily keep up with a 600 watt transistor amp on this speaker due to this issue. A 600 watt transistor amp will only make about 150 watts on a Sound Lab due to the impedance. A tube amp will not loose so much power on this account.

It might help to understand something about how ESLs operate, which is to say that they work much better with an amplifier that behaves as a power source rather than a voltage source.

Don't worry if you did not understand that last sentence. Just read this article, its a quick read and there is almost no math :)

http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php

So if you plan to bi-amplify, you might be able to do just fine with a tube amp that makes only about 60 watts for the top end. This depends somewhat on your room. The reason people use high power transistors is because of the impedance in the bass, while a 200 watt tube amp is usually enough power in many listening situations.

Now if you apply the mods that I mentioned earlier, which are easy to do, the speaker gets a lot easier to drive. Customers have reported that our MA-1 had unlimited power (could not clip them) in their system after they did the mod. IOW the driver is fairly efficient, most of the problem of drivability has to do with the back panel. So if you do this and you bi-amplify, a 60 watt tube amp might do the trick, and will sound better than a transistor amp on that load.

Something to think about!
More to discover